I change my oil every 5k, regardless of what the manufacturer or oil company says, fresh oil is good oil, always synthetic. My air filter is changed when its dirty, with an on road car isn't often, but keep an eye on it. Other than that i would look up tranny/diff flushes as i'm unsure on the change. Maybe every 60k miles for both of them sounds reasonable. If you have an MT you'll notice when it needs to be changed as it'll get a tad notchier than usual(so i've read). If you have an untuned 135i, sparkplugs at 60k, for a 128, 100k. If you are a tuned 135i, i would say every 30-35k depending on how extreme the tune is.